Microinjected oligonucleotides complementary to the alpha-sarcin loop of 28 S RNA abolish protein synthesis in Xenopus oocytes.
The integrity of the alpha-sarcin loop in 28 S ribosomal RNA is critical during protein synthesis. The toxins alpha-sarcin, ricin, Shiga toxin, and Shiga-like toxin inhibit protein synthesis in oocytes by attacking specific nucleotides within this loop (Ackerman, E.J., Saxena, S. K., and Ulbrich, N. (1988) J. Biol. Chem. 263, 17076-17083; Saxena, S.K., O'Brien, A.D., and Ackerman, E.J. (1989) J. Biol. Chem. 264, 596-601). We injected Xenopus oocytes with deoxyoligonucleotides complementary to the 17-nucleotide alpha-sarcin loop of Xenopus 28 S rRNA. Only injected oligonucleotides fully covering the alpha-sarcin loop or slightly beyond inhibited oocyte protein synthesis. Shorter alpha-sarcin domain deoxyoligonucleotides complementary to the alpha-sarcin and ricin sites but not spanning the entire loop were less effective inhibitors of protein synthesis. The alpha-sarcin domain oligonucleotides covering the entire loop were more effective inhibitors of protein synthesis than injected cycloheximide at equivalent concentrations. Control oligonucleotides complementary to nine other regions of Xenopus 28 S rRNA as well as universal M13 DNA sequencing primers had no effect on oocyte protein synthesis. Oligonucleotides complementary to the highly conserved alpha-sarcin domain therefore represent an alternative to catalytic toxins for causing cell death and may prove effective in immunotherapy.
Saxena
S K
SK
Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Ackerman
E J
EJ
D000818:Animals; D001483:Base Sequence; D004722:Endoribonucleases; D005260:Female; D005656:Fungal Proteins / Q000494:pharmacology*; D008845:Microinjections; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D015345:Oligonucleotide Probes; D009865:Oocytes / Q000378:metabolism*; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D012335:RNA, Ribosomal / Q000235:genetics*; D012339:RNA, Ribosomal, 28S / Q000187:drug effects / Q000235:genetics*; D014981:Xenopus
D005656:Fungal Proteins; D015345:Oligonucleotide Probes; D011500:Protein Synthesis Inhibitors; D012335:RNA, Ribosomal; D012339:RNA, Ribosomal, 28S; C014801:alpha-sarcin; D004722:Endoribonucleases